Apparatus for preparing very fine lustrous metal particles



May 13, 1941.

J. ECKART 2,241,848 APPARATUS FOR PREPARING VERY FINE LUSTROUS METALPARTICLES Filed Jan. 20, 1938 2 Sheetsl-Shet 1 lm/enfantfaaZ 5: kg r Z BMay 13, 1941. J, KART 2,241,848

APPARATUS FOR PREPARING VERY FINE LUSTROUS METAL FARTICLES Filed Jan.20, 1958 z Sheets-Sheet 2 Inventor:

- Lzco5 Zeke/'2 By Patented May 13, 1941 APPARATUS FOR PRE LUSTROUS METPARING VERY FINE AL PARTICLES Jacob Eckart, Furth, Germany, assignor tothe firm Standard Bronzefarben Werke Carl Eckart, Furth, Bavaria,Germany Application January 20,

1938, Serial No. 185,963

In Germany October 14, 1935 12 Claims.

My invention relates to an apparatus for preparing very fine highlylustrous metal particles, such as are required for making bronze paintsand metal powder.

The apparatus consists of a combined ball and hammer or beating mill inwhich the Working 'material consisting of small platelets is beaten thinand smooth. The end product consists of scales of the maximum smallnessand thinness having a smooth, highly lustrous surface.

On the combined ball and hammer mill there is an arrangement by means ofwhich a continuous equalisation of the inner air and the outer air ismade possible. By means of the air equalisation a slow, harmlessoxidation of the working material is brought about during the workingprocess.

The accompanying drawings show one constructional example of theapparatus according to the invention. In the drawings Figure 1 shows thecombined ball and hammer mill in elevation,

Figure 2 shows an end view of the mill,

Figure 3 shows a section through the wall of the mill at the place wherethe air equalisation occurs,

Figure 4 shows a diagrammatic cross section through the mill, and

Figure 5 gives a schematic representation of the hammer motion in thecross section of the mill.

The combined ball and hammer mill consists of a drum a whichaccommodates rolling balls 72. of varying size. Throughout the length ofthe drum there are anvil elements It on which at least one hammer gfalls when the drum rotates.

In Figures 4 and 5 the arrangement, and manner of working, of a hammer gis shown schematically. The hammer operates alternately on three anvilelements k, which latter, arranged in triangular form, are fixed withinthe drum (1 and rotate with the drum. The hammer g is rotatably orpivotally suspended at the point f. The point 1 is outside the middleaxis of the drum a and is stationary, and therefore does not partake ofthe rotation of the drum. Thus the center j which is the pivot point ofsuspension for the hammer g is immovable or stationary with respect tothe rotating drum a and each anvil leis at the same distance from theaxis center of the drum a. In a preferred form of the invention ofconstruction the hammer g is suspended from a point 1 on a link I, Fig.4, and this link is keyed or otherwise suitably secured on the centerpoint or shaft f". The shaft j" is stationary at all times and the druma rotates around the shaft ,f" as an axis, I

When the hammer g, as shown in Figures 4 and 5, rests or contacts on oneof the three anvil elements k, then, while the drum 0. is rotatingcounterclockwise in the direction of the outer arrow,

the hammer is taken along by the anvil element,

reached a position where itis in the path of the descending hammer.

The interior space of the drum a is only partly filled with the workingmaterial. At the moment at which the hammer g falls on to the next anvilelement lc, hammer and anvil element are both within the workingmaterial. That portion of the working material, therefore, which liesabove or in the path of the impact surface of the anvil element, isbeaten by the descending, hammer.

The balls h' are always situated within the working material and arecaused to roll about by the rotation of the drum. slowly. As a resultthe balls are not raised so high that they could fall down freely. Theballs roll about in the working material but they do not fall down on tothe material in the drum to be worked.

By the simultaneous action of the hammer g and of the balls 11. theworking material is reduced in size and texture. The working process isfinished when the small platelets which form the starting material areconverted into smooth highly lustrous scales of the greatest finenessand thinness.

As is shown in Figures 1 and 2, a pipe b leads into the mill a. Throughthis pipe fresh air is led into the drum. At one place in the drum walla number of holes or perforations c are arranged. The perforated placeis covered in the interior with a filter cloth d. On the filter cloththere lies in the interior a perforated plate e. The holes orperforations j of the plate e correspond with the holes c in the wall ofthe drum.

The holes 0 and ,f effect a continuous equalisation between the innerair and the outer air during the working process. As a result of theshaking which the drum experiences during the working process, thematerial being ground is continuously shaken away from the holes j-c sothat the said holes remain free for the passage of air. The filter clothd permits the passage of air The drum rotates Owing to the mechanicalheating of the working material a slow temperature rise takes place inthe operating ball and beating mill. By means of the continuous airequalisation, a temperature rise up to the ignition temperature of theworking material is prevented. A gradual, slight and harmless oxidationtakes place at the surface of the small metal particles. In this way,explosion in the interior of the working mill is prevented.

I claim:

1. An apparatus for making very fine, lustrous metal particles,comprising a rotatable drum, at least two anvil elements fixed incircumferential spaced relation relative to each other within the drumto rotate therewith around the center axis of the drum and each elementbeing spaced a substantial distance from the peripheral Wall of the drumand the axis of rotation of the drum, each anvil element having a fiatimpact surface in a plane approximately parallel to the axis of rotationof the anvil elements and a side surface of each element facing the axisof rotation being directed rearwardly from its impact surface to clearthe path of movement of the hammer, and

. a hammer suspended to swing in the drum from a fixed point which isspaced below the longitudinal center axis of the rotating drum and isadapted to successively strike the impact surface of each anvil element,the suspension distance of the hammer being less than the radialdistance of each anvil element and said hammer after striking one of theanvil elements being carried along by said last-mentioned element in thedirection of rotation of the drum but due to the off-center suspensionof the hammer it is gradually pulled off from the last-mentioned elementuntil it clears the edge of its impact surface whereupon the hammerfollows an unrestricted movement in the direction counter to thedirection of rotation of the drum and falls and strikes the impactsurface of the following or other anvil element.

2. An apparatus according to claim 1 in which each anvil element iswedge shaped with the wedge portion extending rearwardly of the impactsurface and arranged parallel to the longitudinal axis of the drum.

JACOB ECKAR'I'.

